An Analytical Investigation of DC/DC Power Electronic Converters With Constant Power Loads in Vehicular Power Systems

Stability of multi-converter power systems, which exist in advanced more electric vehicles, is of great importance. The stability issue is investigated in this paper, and design considerations and limitations of the methods that stabilize the open-loop converters are presented. By stabilizing the open-loop converter, it is shown that the feedback loop design is usually translated into a conventional feedback design task. The behavior of the unstable converter is also discussed, and a method for decreasing the amplitude of the output voltage oscillations is proposed. The model of a tightly regulated practical converter is presented. This model is used to decide how much damping should be added to make the feeder converter stable. Furthermore, because we have this information about the load converter, the feeder converter can be redesigned so that it does not see the load converter as a constant power load.      

Modified Pulse-Adjustment Technique to Control DC/DC Converters Driving Variable Constant-Power Loads

Multiconverter-distributed DC architectures have been utilized for power distribution in many applications such as telecommunication systems, sea and undersea vehicles, an international space station, aircraft, electric vehicles, hybrid-electric vehicles, and fuel-cell vehicles, where reliability is of prime concern. The number of power-electronic converters (AC/DC, DC/DC, DC/AC, and AC/AC) in these multiconverter electrical power systems varies from a few converters in a conventional land vehicle, to tens of converters in an advanced aircraft, and to hundreds of converters in the international space station. In these advanced applications, power-electronic converters might need to have a tight output-voltage regulation. From the output perspective, this property is highly desirable. However, since power-electronic converters are efficient, tight regulation of the output makes the converter appear as a constant-power load (CPL) at its input side. Dynamic behavior of CPLs is equivalent to negative impedance and, therefore, can result in instability of the interconnected power system. In order to mitigate the instability of the power converters loaded by CPLs, this paper presents the pulse-adjustment digital control technique. It is simple and easy to implement in application-specific integrated circuits, digital-signal processors, or field-programmable gate arrays. Moreover, its dynamic response is fast and robust. Line and load regulations are simply achievable using this technique. Analytical, as well as simulation and experimental results of applying the proposed method to a DC/DC buck-boost converter confirm the validity of the presented technique.     

有效负载电阻——评估DC/DC转换器效率的新方案

本文提供另外一种方法,作为电源的评估工具以测量效率。这个方法行之有效,且与输出电压和温度的相关性较小。     

单周期控制有源电力滤波器直流分量抑制新方法

单周期控制有源电力滤波器具有检测量少、控制器结构简单以及鲁棒性强等优点。传统的单周期控制有源电力滤波器以峰值电流检测的控制方式和纹波电流的存在导致补偿后的电源电流中含有直流分量。文中分析了直流分量的产生机理,提出在控制电路中加入并联谐振电路来消除纹波电流对补偿性能的影响,从而抑制直流分量的产生。实验结果证明了所提方法的正确性和可行性。     

Realization of Parasitics in Stability of DC–DC Converters Loaded by Constant Power Loads in Advanced Multiconverter Automotive Systems

Distributed DC power systems are becoming increasingly common in advanced automotive systems. Constant power load (CPL) behavior of tightly regulated DC-DC converters in multiconverter power systems is equivalent to the dynamic negative impedance, destabilizing the DC bus and, consequently, the system. Various techniques have been developed to control ideal/lossless converters loaded by CPLs. Loss components significantly enhance the stability of the cascaded converters. In this paper, the effects of parasitics in the behavior of DC-DC converters loaded by CPLs are investigated. Furthermore, the stability of power converters loaded by CPLs in parallel to conventional constant voltage loads in the presence of loss components is analyzed. Design criteria are presented for converter operation in continuous and discontinuous conduction modes, which gives recommendations on the design of multiconverter DC power systems to avoid negative impedance instability. The proposed stable operation criteria are validated with hardware prototypes and simulation analyses.     

A Novel Constant Power Control Circuit for HID Electronic Ballast

This paper presents a constant power control circuit for a three-stage high-intensity discharge (HID) electronic ballast. The three-stage electronic ballast is composed of a boost pre-regulator to achieve a high power factor, a DC/DC buck converter to regulate lamp current with constant lamp power, and a full-bridge inverter to drive the HID lamp with a low-frequency ac squarewave current. The buck converter operating in current mode utilizes current sense level-shift technique to achieve constant power output. The proposed constant power control circuit is easily designed and implemented for the three-stage HID electronic ballast. Finally, a laboratory prototype of a 70 W HID electronic ballast is implemented. The measured results show that the proposed ballast can be applied for various HID lamps with low lamp power variation (less than 0.6%).     

一种新型DC／DC变换器输出滤波器的研究

输出滤波器是DC／DC变换器的重要组成部分，滤波器的大小往往决定了整个电源的体积和重量，同时与整个系统的稳态性能和动态性能等指标有着密切的联系。如何减小输出滤波器中磁性元件的体积成为目前开关电源研究的一个重要方向。本文针对采用并联方式运行的低压大电流的电源，从理论上提出了一种电感集成的新型二级LC输出滤波器，该滤波器在一定程度消除了输出滤波电感的直流磁化，减小了输出滤波器的体积，从而减小了整个电源的体积和重量，实现了电源的小型化，轻型化。从仿真结果来看，这种滤波器提高了DC／DC变换器的稳态性能和动态性能。     

DC/DC变换器输入阶跃响应测试方法研究

介绍了DC/DC变换器输入阶跃响应的概念和测试原理,对该参数的测试技术进行了探索,开发出适合的测试方法和测试系统。通过产品的测试,验证了测试方法和测试系统的准确性。该测试方法符合SJ20646-97《混合集成电路DC/DC变换器测试方法》的规定。该测试方法和系统适用于大动态输入范围和大功率DC/DC变换器输入阶跃响应的测试。     

用DC/DC转换器最大化便携媒体播放器电源效率

如果你问十几岁的青少年最希望他们的MP3是什么样的,他们的回答总是相同的-他们希望自己的MP3具有很酷的外形以及优异的音质,另外他们还希望电池工作时间越长越好.     

A Novel Method of Active Power Noise Cancellation in I/O Buffers

This paper presents a scheme to reduce the on-die voltage noise that occurs due a buffer switching event. Both output and input buffer switch events are addressed. A generic power delivery network (PDN) model with parasitic inductance is assumed. A change in current ( ${rm di}/{rm dt}$) across the inductor is considered the primary cause of the voltage noise. On-die decoupling capacitance is traditionally added to the power delivery network to address this problem and to limit the droop. The method described in the paper shows a principally different approach. The maximum ${rm di}/{rm dt}$ is managed to reduce the voltage noise. It is proposed to send to a buffer a current waveform from an external supply or to recycle charge from a locally charged capacitance when the ${rm di}/{rm dt}$ occurs, thus substantially reducing the on-die voltage noise. Alternatively, at a given acceptable level of voltage noise the on-die capacitance can be reduced, providing significantly lower product cost. This paper provides theoretical and modeling background of the proposed schemes and includes simulation results on several performance characteristics.      

Improved Direct Power Control of Grid-Connected DC/AC Converters

This paper proposes new direct power control (DPC) strategies for three-phase dc/ac converters with improved dynamic response and steady-state performance. As with an electrical machine, source and converter flux, which equal the integration of the respective source and converter voltage, are used to define active and reactive power flow. Optimization of the lookup table used in conventional DPC is outlined first so as to improve power control and reduce current distortion. Then, constant switching frequency DPC is developed where the required converter voltage vector within a fixed half switching period is calculated directly from the active and reactive power errors. Detailed angle compensation due to the finite sampling frequency and the use of an integral controller to further improve the power control accuracy are described. Both simulation and experimental results are used to compare conventional DPC and vector control, and to demonstrate the effectiveness and robustness of the proposed control strategies during active and reactive power steps, and line inductance variations.      

DC/DC变换器稳态建模的教学方法

本文介绍了一种为DC/DC变换器建立稳态模型,并利用稳态模型分析变换器的稳态工作特性的教学方法和研究思路。本方法所建模型既可以体现变换器的DC/DC变换功能,又可以包含变换器在稳态工作时的主要损耗。模型结构简单,运用简单的电路分析方法,就能够较为简便地得出直流变换器稳态工作时的主要电气特性。本文所介绍的建模方法是研究直流变换器稳态工作特性的有力工具,在教学研究中都具有较高的推广价值。     

PWM型DC/DC开关变换器的自抗扰控制策略

文章介绍了自抗扰控制器的原理和结构。结合开关变换器脉动和非线性的特点，介绍了自抗扰控制器在DC—DC开关变换器中的应用；并对具体的Buck电路进行了建模、仿真和实验，结果验证了控制策略的优良性。     

基于8位微控制器的参数自调整模糊控制DC/DC变换器

提出了一种基于8位微控制器实现的用于控制DC／DC变换器输出电压的参数自调整模糊控制方法。用参数自调整的策略来优化常规模糊控制器，提高了DC／DC变换器的控制性能。实验结果表明，所提出的新控制方法不仅具有良好的控制性能，而且容易用成本较低的8位微处理器来实现。     

Stabilizing the Frequency of Hysteretic Current-Mode DC/DC Converters

A systematic investigation of methods to stabilize the operating frequency of hysteretic current-mode dc/dc converters through control of the current hysteresis is presented. The control laws for every power stage are derived, and two open-loop and two closed-loop circuits are shown and analized in detail. The interaction of the major voltage control loop and the frequency control circuitry is also investigated for buck converters. It is shown that, if the average inductor current is programmed, the two mechanisms are independent, while if the peak inductor current is programmed, they are not. The frequency control circuitry in the latter case decreases the phase margin of the voltage control loop and can lead to instability. Simple circuits are developed to implement the superior average inductor-current programming. As a consequence of being controlled via the current hysteresis, the operating frequency cannot be stabilized in the light mode, where VO/RL < IH/2. In the special case, where the frequency of the converter is stabilized by a phase-locked loop, a method and circuit are shown to solve this problem and achieve constant frequency operation at any load.     

电力电子变换器中滤波电容参数设计方法

在电力电子变换器中,滤波电容可以抑制电压脉动,消除谐波,其参数大小对变换器的性能有着重要影响。本文首先分析滤波电容器的特性,得出影响电容器滤波效果的各个因素,然后介绍了几种常用的滤波电容器参数设计方法,最后通过一个全桥变换器进行了仿真验证,有助于学生更好地掌握滤波电容器的参数设计。     

Performance Evaluation of a Novel Hybrid Multipulse Rectifier for Utility Interface of Power Electronic Converters

This paper presents an improved analysis of a novel programmable power-factor-corrected-based hybrid multipulse power rectifier (PFC-HMPR) for utility interface of power electronic converters. The proposed hybrid multipulse rectifier is composed of an ordinary three-phase six-pulse diode-bridge rectifier (Graetz bridge) with a parallel connection of single-phase switched converters in each three-phase rectifier leg. In this paper, the authors present a complete discussion about the controlled rectifiers' power contribution and also a complete analysis concerning the total harmonic distortion of current that can be achieved when the proposed converter operates as a conventional 12-pulse rectifier. The mathematical analysis presented in this paper corroborate, with detailed equations, the experimental results of two 6-kW prototypes implemented in a laboratory.     

LHB1900系列混合集成DC／DC变换器的研制

ＬＨＢ１９００系列混合集成ＤＣ／ＤＣ变换器，采用厚膜混合集成电路技术制作，电路采用恒频４００ＫＨｚＰＷＭ推挽结构，功率密度５００ｍＷ／ｍ３，效率达８０％，本文简要介绍ＤＣ／ＤＣ变换器电路设计及工艺制作技术，该系列ＤＣ／ＤＣ变换器可用于军事、航空航天及其它可靠性要求高的领域。     

Nonlinear Modeling of DC/DC Converters Using the Hammerstein's Approach

This paper deals with the modelling of highly nonlinear switching power-electronics converters using black-box identification methods. The duty cycle and the output voltage are chosen, respectively, as the input and the output of the model. A nonlinear Hammerstein-type mathematical model, consisting of a static nonlinearity and a linear time-invariant model, is considered in order to cope with the well-known limitations of the more common small-signal models, i.e. the entity of the variations of the variables around a well-defined steady-state operating point and the incorrect reproduction of the steady-state behavior corresponding to input step variations from the above steady-state operating point. The static nonlinearity of the Hammerstein model is identified from input-output couples measured at steady state for constant inputs. The linear model is identified from input-output data relative to a transient generated by a suitable pseudorandom binary sequence constructed with two input values used to identify the nonlinearity. The identification procedure is, first, illustrated with reference to a boost DC/DC converter using results of simulations carried out in the PSpice environment as true experimental results. Then, the procedure is experimentally applied on a prototype of the above converter. In order to show the utility of the Hammerstein models, a PI controller is tuned for a nominal model. Simulation and experimental results are displayed with the aim of showing the peculiarities of the approach that is followed.     

DC/DC转换器中电流采样电路的设计

设计了一种用于DC/DC开关电源转换器的新型电流采样电路.常见的电流采样电路是通过检测采样管串联电阻上压降来得到采样电流,而该采样电路是通过检测开关管串联电感上压降来得到采样电流的.由于后者所需电阻更少,从而降低了采样电路的功耗,提高了效率;并且由于电感上压降对采样电流变化的灵敏度更高,有效地提高了采样的精度.